my ($value,$error) = my_sub(input => 'who', inny => 'what');
unless ($value) {
    my_abort ("There was an error: ",$error);
}

##</code><code>##

sub my_sub {
    my %args = {
        input => undef,
        inny  => undef,
        @_
    };
    return(undef,"Missing inny") unless $args->{'inny'};
    # do some stuff
    if ($problem) {
        return(undef,$error_msg);
    }
    return($value,undef);
}